bpo-40170: Convert PyObject_IS_GC() macro to a function (GH-19464)
diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst
index 4cab0f5..eee114c 100644
--- a/Doc/c-api/gcsupport.rst
+++ b/Doc/c-api/gcsupport.rst
@@ -60,6 +60,15 @@
followed by the :c:member:`~PyTypeObject.tp_traverse` handler become valid, usually near the
end of the constructor.
+
+.. c:function:: int PyObject_IS_GC(PyObject *obj)
+
+ Returns non-zero if the object implements the garbage collector protocol,
+ otherwise returns 0.
+
+ The object cannot be tracked by the garbage collector if this function returns 0.
+
+
.. c:function:: int PyObject_GC_IsTracked(PyObject *op)
Returns 1 if the object type of *op* implements the GC protocol and *op* is being